In Japan, as is often the case with tires for trucks and buses in particular, a used tire whose tread wears away is reused as a retreaded tire by subjecting the used tire to rework so as to bond a new tread onto the used worn tire (for example, refer to Patent Document 1 or the like). In countries other than Japan, use of retreaded tires is common not only for tires for trucks and buses but also for tires for passenger cars.
A process for producing such a retreaded tire is achieved by removing unnecessary rubber from the tread surface of the used tire in a buffing process so that the height thereof is reduced to a required height; and bonding a new tread rubber onto the tire after the removing as a base tire.
However, since the degree of the tread wear differs among used tires, the buffing step of obtaining a base tire takes various lengths of time, and requires a considerably long time.
With this taken into consideration, in order to produce retreaded tires which fall within a certain range of dimensional specifications under good production management and process management, control on the lengths of the buffing time, the depth of buffing, and the like, at the time of the retreading process of individual used tires becomes important for the purpose of increasing the productivity. Accordingly, improvement in process simplification, uniformity, and the like in terms of the process management and quality control has been demanded for the purpose of enhancing the productivity of retreaded tires.